Uncertainty and statistics of dislocation-oxide interactions on strength and creep failure of oxide dispersion strengthened steels

Abstract

Oxide dispersion strengthening (ODS) steels exhibit excellent mechanical and creep properties due to the nanoscale oxide particles as barriers to dislocation motion, for the great application potentials to structural components of advanced nuclear power plants. However, the classical ODS model described by the Orowan mechanism or cutting mechanism only depends upon a single average size, ignoring uncertainty and statistics of dislocation-oxide interactions induced by the spatial and dimensional random distribution of oxide particles. When the oxide particle size is larger than the critical size to determine the interaction mechanism transformation from cutting to looping, the Orowan mechanism and cutting mechanism would exist simultaneously. Here we propose a modified ODS model for strength and creep rate considering the spatial distribution and size distribution of oxide particles, which is more consistent with the experimental result compared to the classical ODS model. In addition, the contribution of oxide particles to the yield strength and creep strength is evaluated quantitatively for various precipitate sizes and volume fractions. It is believed that this model provides an analytical framework to accurately predict the strength and creep rate of ODS steels.